Photographic process for producing prints stabilized against print-out



United States Patent M 3,278,307 PHOTQGRAPHIC PROCESS FQR PRODUCING PRINTS STABILIZED AGAINST PRINT-OUT Paul H. Stewart and John W. Reeves, Jr., Rochester, N.Y.,

assignors to Eastman Kodak Company, Rochester,

N.Y., a corporation of New Jersey No Drawing. Filed Nov. 21, 1961, Ser. No. 154,045

17 Claims. (Cl. 96--62) This invention relates to photography and more particularly to light-sensitive elements adapted to the production of prints having reduced propensity to print-out.

I11 conventional photographic processes, silver halide emulsion layers are exposed to a subject, a silver image is developed therein by means of an alkaline photographic developing solution, and the emulsion is then fixed'out with a solution of a silver halide solvent such as acid hypo following which the print is washed to remove hypo and other salts. The mentioned fixing step removes a large proportion of the undeveloped silver halide which would otherwise print out, that is, darken upon exposure to light, and thus produce undesirable density in the highlights of the print. The washing step often requires considerable time depending upon a number of factors such as the volume of wash water and the amount of salts absorbed by the print, and serves to remove the hypo and dissolved silver remaining in the prints; otherwise stain will appear in the highlights of the print and the silver image will eventually fade or change color due to sulfurization.

We have discovered a simple photographic process which obviates the fixing and washing of photographic prints and merely entails exposure of an emulsion and subsequent treatment with plain water for as little as 15 seconds. No subsequent fixing or washing steps are required to produce prints having very low print-out propensity.

According to our invention, a sensitive element is employed containing a conventional silver halide emulsion, predominately silver bromide, having inherently low printout propensity compared to, for example, silver chloride, and integral with and contiguous to the silver halide are an alkaline material such as sodium metaborate, a 3- pyrazolidone silver halide developing agent and preferably ascorbic acid, as well as a desensitizer for silver halide. Thus, the 3-pyrazolidone silver halide develop ing agent, the alkali and desensitizer may be present in the emulsion or one or more of these three ingredients may be present in a layer effectively adjacent to the emulsion layer. In a preferred embodiment, the developing agent and alkali are present in a layer overlying the silver halide emulsion layer and the desensitizer is contained in a layer thereover. In another embodiment the desensitizer is contained in the emulsion layer and the developing agent and alkali are present in one or more layers coated thereon. The following examples will serve to illustrate our invention.

Example I A fine-grain gelatin silver bromoiodide emulsion containing approximately 95 mole percent silver bromide and 5 mole percent silver iodide was coated on a paper support at a coverage of about 1900 square feet per mole of silver. The emulsion was then overcoated with a solution of a mixture of 50 grams sucrose, 48 grams of 20 percent aqueous gelatin solution and 500 cc. of the following developer solution:

3,278,307 Patented Oct. 11, 1966 G. 1-phenyl-3-pyrazolidone 2.5 Na SO Sodium ascorbate 15.0 KBr 1.0 Sodium metaborate 45.0 S-methylbenzotriazole 0.02

Water to make 1 liter.

the coating being applied so as to use 9.0 grams solution per square foot of coating surface. A sample of this coating was exposed to a subject and then washed with running water at 20 C. for 15 seconds, then air dried. As a result, a silver image was developed in the emulsion layer and the print had reduced print-out propensity. In order to test the resistance of the print to print-out, a sample was exposed to northern daylight at 50 percent R.H. (relative humidity) and F. for 1 week with the result that a minimum density of 0.20 was obtained in the highlight regions of the print. Another print was exposed to 50 foot-candles illumination for 7 hours at 100% R.H.75 F. to obtain a minimum density of 0.15. In order to demonstrate the advantage of using liquid water compared to water vapor for developing the print, exposed samples of the original emulsion were subjected to treatment with saturated air at C. for 5 seconds, and samples of the prints subjected to 1 week exposure to northern daylight at 50 percent R.H. at 75 F., with the result that a higher minimum density of 0.6 was obtained, and 50 foot-candle illumination at percent R.H.75 F. of another print for 1 hour gave a higher minimum density of 1.0.

Example [I The present example illustrates the advantage of using a desensitizer for silver halide in the process.

Example I was repeated except that the emulsion layer carrying the overcoa-ting layer of developing agent and alkali was overcoated with a 0.01 percent (by volume) solution of 6-chloro-4-nitrobenzo-1,2,3-triazole in isopropyl alcohol. A sample of the resultant element was exposed and processed by merely treating it with running water for 15 seconds with the result that the print had zero minimum density after 1 week exposure to north light and 0.05 minimum density after 7 hours exposure to 50 foot-candle illumination at RH. and 75 F. Other samples of the element processed with water saturated air, rather than liquid water, showed an undesirable increase in minimum density. Additional tests over a range of concentration of the above desensitizer in the emulsion of from 0.1 to 20 grams per mole of silver halide showed that substantial improvement in print stability was obtained at concentrations between about 1 to 20 grams of desensitizer per mole of silver halide although some speed loss was sustained (0.4 log E) at the 20-gram level. A preferred range is from about 1 to 10 grams of desensitizer per mole of silver halide.

Example III To a fine-grained bromoiodide emulsion of the type described in Example I was added 1 gram of the desensitizer 6-chloro-4-nitrobenzo-l,2,3-triazole per mole of Si]: ver halide. This emulsion was then coated on a barytacoated paper support at a coverage of about 500 square feet per mole silver. The emulsion layer was then overcoated with a solution of 50 grams sucrose dissolved in 500 cc. of the l-liter developer composition of Example I at a coverage of 6 grams per square foot. An exposed sample of this element was processed with water for 15 seconds and showed no increase in minimum density after 2 weeks exposure to north daylight.

This example indicates that the best stability is obtained by use of the desensitizer in the emulsion rather than in an overcoating layer although very useful results are obtained in either case.

Example IV This example illustrates the improvement effected by use of a 3-pyrazolidone developing agent rather than other developing agents in the process of the invention.

Example II was repeated except using in the developer solution, which was coated upon the emulsion layer, grams of Elon and 24 grams of hydroquinone in place of the 1-phenyl-3-pyrazolidone-ascorbic acid combination. When the element was exposed and water-processed for seconds and the print illuminated with north daylight for 7 days, as in Example II, the minimum density increased from 0.12 to 0.60 whereas the sample processed as in Example II under the same conditions showed zero minimum density.

Example V Example II was repeated except that isopropyl alcohol solutions of the desensitizers indicated below were coated over the developer-containing emulsion layer overlying the silver halide emulsion layer with the result shown.

( 1 1-methyl-2-( p-nitrostyryl) -6-ethoxy-quinolinium p-toluenesulfonate (2) 2-(p-diethylaminophenyliminomethyl)-1,6-

dimethylquinolinium chloride (3) 2-(p-dimethylaminophenyliminomethyD-benzothiazoleethoethylsulfate Other 3-pyrazolidone silver halide developing agents may be used in the sensitive elements in the place of 1-phenyl-3-pyrazolidone particularly in combination with ascorbic acid, e.g., 1-p-tolyl-3-pyrazolidone, 4-methyl-3- pyrazolidone, 1-phenyl-4,4-dimethyl-3-pyrazolidone, l-(pp-hydroxyethylphenyl)-3-pyrazolidone and other 3-pyrazolidones disclosed by the James et a1. U.S. Patent 2,751,300, granted June 19, 1956. While the 3-pyrazoli dones per se can be used in the sensitive element to good advantage, the best results and consequently prints least susceptible to print-out after processing in water are ob tained when the 3-pyrazolidones are used in combination with ascorbic acid, as described in the above examples. When the 3-pyrazolidones are used in the absence of ascorbic acid, it may be desirable to use larger quantities than indicated in the above examples and it may be desirable to use warm water for developing the prints.

The desensitizers for silver halide which are integral with and contiguous to the silver halide of the emulsions and preferably is contained in the emulsions, are those well known in the art and preferably the desensitizers which are most strongly absorbed to silver halide and are substantially water insoluble such that they are not to any great extent removed from the sensitive element during the mentioned brief treatment with water. The preferred classes of desensitizers are heterocyclic compounds containing a benzene ring having at least one nitro group attached thereto, such as S-nitrobenzo-1,2,3-triazole, 4- nitro-6-chlorobenzotriazole and 2,3-dimethyl-6-nitrobenzothiazolium p-toluenesulfonate, styryl dyes having at least one benzene nucleus to which is attached at least one nitro group such as 1-methyl-2(p-nitrostyryl)-6- ethoxyquinolinium p-toluenesulfonate, and anil dyes which are characterized (Mees, Theory of the Photo graphic Process, 1942, page 1043) as containing a nitrogen atom within a chain separated from nitrogen atoms at the ends of the chain, by an even number of carbon atoms such as 2-(p-diethylaminophenyliminomethyl)-1,6- dimethylquinolinium chloride and Z-(p-dimethylaminophenyliminomethyl)-3-ethylbenzothiozolium ethosulfate.

The silver halide emulsions used in the sensitive element are those well known in the art having inherent relatively low print-out propensity compared for example to silver chloride, preferably emulsions predominately silver bromide, for example, bromoiodide emulsions containing or more mole percent silver bromide and the remainder silver iodide.

The alkaline component of the sensitive element includes organic and inorganic alkali such as alkali metal hydroxides and metaborate and tetraalkyl ammonium hydroxides in quantity sufiicient to accelerate development to the extent that development of the emulsion is complete under the mentioned conditions such as 15 seconds.

The water treatment step which initiates the development of the exposed emulsion, as illustrated in the above examples requires only about 15 seconds time to produce a fully developed and stabilized image. The time of water treatment may vary, for example, cold and warm water, respectively, may reduce or extend the time of treatment. Longer times such as several minutes wash of the print are not objectionable but are not necessary if the process is carried out as illustrated in the examples. The water should be applied to the exposed emulsion layer uniformly as a stream of water particularly to bring about uniform development of the emulsion and then to effect removal of soluble emulsion components and products of development.

What we claim is:

1. A light-sensitive photographic element adapted to form a silver image, comprising a support having thereon a silver halide emulsion layer in which the said silver halide is predominately silver bromide, and contiguous to the silver halide, alkali, a 3-pyrazolidone silver developing agent, and a desensitizer for silver halide of the class consisting of heterocyclic compounds containing a fused benzene ring, said benzene ring having at least one nitro group attached thereto, styryl dyes having at least one benzene ring to which is attached at least one nitro group, and anil dyes.

2 The element of claim 1 wherein the desensitizer is present in the emulsion layer.

3. The element of claim 1 wherein the desensitizer, alkali and developing agent are present in at least one layer overlying the emulsion layer.

4. The element of claim 1 wherein the desensitizer is a member of the class consisting of 4-nitro-6-chlorobenzotriazole, l methyl 2(p-nitrostyryl)-6-ethoxyquin0linium p-toulene-sulfonate, 2-(p-diethylaminophenyliminoethyl)- 1,6 dimethylquinolinium chloride and 2 (p dimethylaminophenyliminomethyl)-3-ethylbenzothiazoliurn ethosulfate.

5. The element of claim 1 also containing ascorbic acid as a silver halide developing agent.

6. A light-sensitive photographic element adapted to form a silver image comprising a support having thereon a silver halide emulsion layer in which the said silver halide is predominantly silver bromide and contiguous to the silver halide, alkali, a 3-pyrazolidone silver developing agent, and a desensitizer for silver halide, said desensitizer being a heterocyclic compound containing a fused benzene ring, said benzene ring having at least one nitro group substituent.

7. A light-sensitive photographic element adapted to form a silver image comprising a support having thereon a silver halide emulsion layer in which the said silver halide is predominantly silver bromide and contiguous to the silver halide, alkali, a 3-pyrazolidone silver developing agent, and a desensitizer for silver halide, said desensitizer being a styryl dye having at least one benzene ring to which is attached at least one nitro group substituent.

8. A light-sensitive photographic element adapted to form a silver image comprising a support having thereon a silver halide emulsion layer in which the said silver halide is predominantly silver bromide and contiguous to the silver halide, alkali, a 3-pyrazolidone silver developing agent, and a desensitizer being an anil dye.

9. A light-sensitive photographic element adapted to form a silver image stabilized against print-out, comprising a support having a silver halide emulsion layer, the silver halide of which is predominately silver bromide, and contiguous with said silver halide, sucrose, l-phenyl- 3-pyrazolidone, sodium sulfite, sodium ascorbate, potassium bromide, sodium metaborate, S-methylbenzotriazole, and 6-chloro-4-nitrobenzo-1,2,3-triazole.

10. A light-sensitive photographic element adapted to form a silver image stabilized against print-out, comprising a support having a silver halide emulsion layer, the silver halide of which is predominately silver bromide, and contiguous with said silver halide, sucrose, l-phenyl- 3-pyraz0lidone, sodium sulfite, sodium ascorbate, potassium bromide, sodium metaborate, 5-methylbenzotriazole, and l-methyl-Z-(p-nitrostyryl) 6 ethoxyquinolinium ptoluenesulfonate.

11. A light-sensitive photographic element adapted to form a silver image stabilized against print-out, comprising a support having a silver halide emulsion layer, the silver halide of which is predominately silver bromide, and contiguous with said silver halide, sucrose, l-phenyl- 3-pyrazolidone, sodium sulfite, sodium ascorbate, potassium bromide, sodium metaborate, S-methylbenzotriazole, and 2- (p-diethylaminophenyliminomethyl) -1,6-dirnethylquinolinium chloride.

12. A light-sensitive photographic element adapted to form a silver image stabilized against print-out, comprising a support having a silver halide emulsion layer, the silver halide of which is predominately silver bromide, and contiguous with said silver halide, sucrose, 1-phenyl- 3-pyrazolidone, sodium sulfite, sodium ascorbate, potassium bromide, sodium metaborate, S-methylbenzotriazole, and 2-(p-dirnethylaminophenyl'iminomethyl) benzotriazole ethoethylsulfate.

13. A method for preparing a photographic silver image stabilized against print-out which comprises exposing to a subject a light-sensitive element comprising a support having thereon a predominately silver bromide emulsion layer and contiguous to the silver halide, alkali, a 3- pyrazolidone silver halide developing agent, and a desensitizer for silver halide of the class consisting of heterocyclic compounds containing a fused benzene ring, said benzene ring having at least one nitro group attached thereto, sty-ryl dyes having at least one benzene ring to which is attached at least one nitro group, and anil dyes, and applying water to the exposed emulsion layer until a silver image has been developed in the emulsion layer in the regions of development and silver halide stabilized against print-out remains in the undeveloped regions of the emulsion layer.

14. The process of claim 13 wherein the densensitizer is present in the emulsion layer.

15. The process of claim 13 wherein the alkali, developing agent and desensitizer are present in at least one layer overlying the emulsion layer.

16. The process of claim 13 wherein the desensitizer is a member of the class consisting of 4-nitro-6-chlorobenzotriazole, 1 methyl-2(p-nitrostyryl)-6-ethoxyquinolinium p-toluenesulfonate, 2 (p-diethylaminophenyliminomethyl) 1,6 dimethylquinolinium chloride and 2-(p-dimethylaminophenylirninomethyl) 3 ethylbenzothiazolium ethosulfate.

17. The process of claim 13 wherein the sensitive element also contains ascorbic acid as a silver halide developing agent.

References Cited by the Examiner UNITED STATES PATENTS 2,131,038 9/1938 Brooker et al. 96109 2,293,261 8/1942 Kendall 96101 2,541,472 2/1951 Kendall et al. 96101 2,614,927 10/1952 Broughton et a1. 96-61 2,669,515 2/1954 Kendall et al. 96101 2,751,297 6/ 1956 Hood et a1. 9666 2,751,300 6/1956 James 9629 2,855,299 10/1958 Rogers 9629 3,041,170 6/1962 Haist et al. 9676 3,080,230 3/1963 Haydn et al. 9676 NORMAN G. TORCHIN, Primary Examiner.

A. D. RICCI, I. T. BROWN, Assistant Examiners. 

13. A METHOD FOR PREPARING A PHOTOGRAPHIC SILVER IMAGE STABILIZED AGAINST PRINT-OUT WHICH COMPRISES EXPOSING TO A SUBJECT A LIGHT-SENSITIVE ELEMENT COMPRISING A SUPPORT HAVING THEREON A PREDOMINATELY SILVER BROMIDE EMULSION LAYER AND CONTIGUOUS TO THE SILVER HALIDE, ALKALI, A 3PYRAZOLIDONE SILVER HALIDE OF THE DEVELOPING AGENT, AND A DESENSITIZER FOR SILVER HALIDE OF THE CLASS CONSISTING OF HETEROCYCLIC COMPOUNDS CONTAINING A FUSED BENZENE RING, SAID BENZENE RING HAVING AT LEAST ONE NITRO GROUP ATTACHED THERETO, STYRYL DYES HAVING AT LEAST ONE BENZENE RING TO WHICH IS ATTACHED AT LEAST ONE NITRO GROUP, AND ANIL DYES, AND APPLYING WATER TO THE EXPOSED EMULSION LAYER UNTIL A SILVER IMAGE HAS BEEN DEVELOPED IN THE EMULSION LAYER IN THE REGIONS OF DEVELOPMENT AND SILVER HALIDE STABILIZED AGAINST PRINT-OUT REMAINS IN THE UNDEVELOPED REGIONS OF THE EMULSION LAYER. 